The LTSP server includes vulnerable LibVNCServer code, which fails to
properly validate protocol types effectively letting users decide what
protocol to use, such as "Type 1 - None" (GLSA-200608-05). The LTSP VNC
server will accept this security type, even if it is not offered by the
server.

Impact

An attacker could exploit this vulnerability to gain unauthorized
access with the privileges of the user running the VNC server.